Well flow controlling method, apparatus and system

ABSTRACT

A method, apparatus, and system for controlling flow of well fluids from a well in response to sensing of a leak in the connections between the components of the well head or fire at the well head for closing off all flow from the well upon the occurrence of such condition. Encompassed is modification of existing installations to carry out the method with a minimum of added equipment or well work-over. Sensing mechanisms responsive to leakage between adjacent connected components of the well head for actuating the closure and responsive to heat from fires at the well head are disclosed. The method, apparatus and system are adapted for multiple string installations and for new installations without modification. The system is also adapted for use with down-hole flow control devices in the well flow conductor.

United States Patent [191 Sizer et al.

[ 1 May 8, 1973 [75] Inventors: Phillip S. Sizer; Albert W. Carroll,

both of Dallas, Tex.

[73] Assignee: Otis Engineering Corporation, Dallas, Tex.

[22] Filed: Mar. 17, 1971 [21] Appl. No.: 125,173

[52] US. Cl. ..166/3l5, l66/53, 166/72 [51] Int. Cl. ..E2lb 43/00 [58] Field of Search ..l37/312; 166/53,

[5 6] References Cited UNITED STATES PATENTS Primary ExaminerMarvin A. Champion Assistant Examiner-Jack E. Ebel AttorneyE. Hastings Ackley ABSTRACT A method, apparatus, and system for controlling flow of well fluids from a well in response to sensing of a leak in the connections between the components of the well head or fire at the well head for closing off all flow from the well upon the occurrence of such condition. Encompassed is modification of existing installations to carry out the method with a minimum of added equipment or well work-over. Sensing mechanisms responsive to leakage between adjacent connected components of the well head for actuating the closure and responsive to heat from tires at the well head are disclosed. The method, apparatus and system are adapted for multiple string installations and for new installations without modification. The system is also adapted for use with down-hole flow control devices in the well flow conductor.

24 Claims, 20 Drawing Figures Patented May 8, 1973 3,731,742

5 Sheets-Sheet l M III/4H2! X iiiin "'7 HI I IN VENTORS 1477' ORIVEV Patented May 8, 1973 5 Sheets-Sheet 5 WELL FLOW CONTROLLING METHOD, APPARATUS AND SYSTEM This invention relates to methods, apparatus and systems for controlling flow of well fluids from a well, and more particularly to such a system responsive to undesirable or unsafe conditions occurring at the well head.

It is one object of the invention to provide improved methods, apparatus and systems for controlling flow of well fluids from a well.

It is an important object of the invention to provide improved methods, apparatus and systems for controlling flow of well fluids from a well particularly responsive to undesirable or unsafe conditions occurring at the well head.

It is a further object of the invention to provide means for shutting off flow of well fluids from a well through a well flow conductor by valve means located in the flow conductor below the master valve.

Still another object of the invention is to provide methods, apparatus and systems for controlling flow of well fluids from a well through the well flow conductor to cut off such flow in response to undesirable or unsafe conditions occurring in or at the well head flow control system and particularly in the Christmas tree of the well head.

Still a further object of the invention is to provide methods, apparatus and systems of the character described which are responsive to the development of leaks in the connections between the components of the Christmas tree or well head system above the tubing hanger, or which are responsive to fire at such well head or Christmas tree, for closing off flow of the well fluids from the well through the flow conductor in the flow conductor below the master valve.

A particularly important object of the invention is to provide a method and system for controlling flow of well fluids from a well through the well flow conductor by means of a flow controlling safety valve disposed in the well flow conductor at the upper end of the tubing or in the tubing hanger below the master valve, and which is biased to an open position by control fluid pressure applied to the valve to move the same to the open position, and wherein the control fluid is confined in an area within the well head at the connection between adjacent components of the well head, whereby separation or leaking of the connections will release the pressure of the control fluid to cause the valve to move to closed position to cut off flow upon the occurrence of such a leak.

It is also an object of the invention to provide sensing means responsive to separating movement of the connections between adjacent components of the well head for relieving the control means which is normally holding the safety valve in open position to permit the same to close upon the occurrence of such a movement.

A further object of the invention is to provide a sensing device for use in a system in practicing the method of the invention which is responsive to heat such as a tire in or adjacent the well head for releasing the control means normally holding the safety valve in open position to permit the valve to move to closed position automatically upon the occurrence of such a fire or the presence of such heat.

A further object of the invention is to provide a control valve which is normally held open by control fluid pressure and which will automatically move to closed position upon release of such control fluid pressure and wherein seal means is provided between the valve and the flow conductor in which the valve is located which is responsive to heat to provide a metal to metal seal between the valve and the flow conductor in the event ofa fire or other similar high temperature condition occurring which would otherwise damage or destroy such sealing means.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIG. 1 is a schematic view of a well installation, partly in elevation and partly in section, showing a down-hole flow control valve connected in the flow conductor or tubing string of the well;

FIG. 2 is a fragmentary schematic view showing the tubing hanger of the well of FIG. I plugged and the Christmas tree thereabove disconnected therefrom;

FIG. 3 is a view similar to FIG. 2 showing an adaptor member or spool connected between the tubing head and the Christmas tree thereabove for carrying out the method of the invention;

FIG. 4 is an enlarged schematic view similar to FIG. 3 showing a flow controlling safety valve anchored in the tubing hanger and sealing with the spacer spool or adaptor of FIG. 3 in condition for operation permitting flow of fluids from the well;

FIG. 5 is a view similar to FIG. 4 showing the valve closed to prevent flow from the tubing string upon the occurrence of a leak between the tubing head and the adaptor flange thereabove;

FIG. 6 is a view similar to FIG. 5 showing a control fluid manifold system in which both the down-hole flow control-ling safety valve and the tubing hanger mounted flow controlling safety valve are each connected to a common source of control fluid responsive to loss of such pressure to close both valves, if desired;

FIG. 7 is a view similar to FIG. 6 showing a further leak sensing structure arrangement connected with the control fluid manifold;

FIG. 7-A is an enlarged fragmentary sectional view of the sensing device used between coupled components of the Christmas tree to sense leaks or separating movement of 'such components;

FIGS. 8-A and 8-8 are enlarged vertical sectional views, partly in elevation and partly in section, of the tubing hanger mounted flow controlling safety valve and control fluid conduit used in the system in practicing the method of FIGS. 4 through 7;

FIG. 9 is a fragmentary sectional view of a sensing device disposed between adjacent flanges of the well head for sensing spreading movement of the flanges, and/or for sensing application of heat thereto;

FIG. 9-A is a, fragmentary vertical sectional view taken on the line 9-A 9-A of FIG. 9;

FIG. 10 is a view similar to FIG. 9 of a modified sensing device in which the separating movement of the flanges is sensed by an electrical microswitch' or electrical means;

FIG. 10-A is a fragmentary vertical sectional view taken on the line 10-A 10-A of FIG. 10;

FIG. 11 is a horizontal cross-sectional view taken between the flanges of a well head connection showing the disposition of a plurality of sensors, such as are shown in FIGS. 9 and 10, between the flanges to sense separating movement or heat applied to the flanges;

FIG. 12 is an enlarged fragmentary vertical view, partly in section and partly in elevation of a modified form of support for the flow controlling safety valve and the modified adaptor for conducting control fluid to the safety valve for controlling actuation of such valve;

FIG. 13 is a schematic view similar to FIG. 1 showing a multiple zone well having parallel flow conductors or tubing strings hung therein from the tubing head and each provided with a flow controlling safety valve in the tubing hanger and upper end of the tubing for separately controlling flow through each of the flow conductors;

FIG. 14 is a fragmentary sectional view similar to FIG. 4 showing a modified form of tubing hanger and tubing head arranged to receive the flow control safety valve of the system and also further illustrating a sensing mechanism for detecting leaks between the flanges of adjacent coupling members between the components of the well head or Christmas tree;

FIG. 15 is an enlarged view, partly in elevation and partly in section, of an electrically controlled safety valve and sensing mechanism for use in practicing the method; and,

FIG. 16 is a view, similar to FIG. 15, showing a modified for of electrically controlled safety valve and In the drawings, FIG. 1 illustrates schematically a typical producing well installation. The usual casing string C extends downwardly from the surface through the usual producing zone Z from which well fluids flow into the casing through the perforations E into the bore of the casing where they will flow upwardly to the lower inlet end of a tubing string or flow conductor T which is sealed at its lower end with the casing by the usual packer P.

A down-hole flow controlling safety valve device V is connected in the tubing string and is of the type generally shown in the patent to John V. Fredd, US. Pat. No. 3,007,669, which is normally biased to a closed position and which is moved to an open position by means of control fluid pressure conducted thereto through a control fluid conductor line L extending inwardly through a gland fitting member G in an exit bushing B connected to the upper end of the casing head A with the usual annular seal ring R sealing between the casing head A and the bushing B. A tubing head H is connected to the upper end of the exit bushing B by bolts in the usual manner, and a seal ring R2 is disposed between the flanges of the bushing and the tubing head to seal therebetween. A tubing hanger or support S is threaded into the bore of the tubing head or otherwise suitably supported in said bore, and the upper end of the string of tubing T is connected to the hanger or support in the usual manner.

Above the tubing head H is the usual master valve M for controlling flow from the well through the bore of the tubing and through the Christmas tree X in the usual manner, the master valve being connected by flanges in the usual manner to the. upper end of the tubing head and to the flow cross K thereabove. The usual seal rings R3 and R4 are disposed between the flanges of the master valve and the tubing head and between the master valve and the flow cross, respectively. The usual wing connections W1 and W2 are connected to the flow cross in the customary manner and a swab valve or crown valve Y is connected to the upper end of the cross and a bull plug and pressure gauge may be connected to the upper end of the crown valve in the customary manner, if desired. The casing head A has a lateral inlet and outlet port provided with a flow line and casing wing valve Al, also in the customary manner.

The down-hole flow controlling safety valve V is preferably installed at a depth several hundred to several thousand feet, or possibly more, in the well to provide means for closing off flow through the tubing string T in the event of the occurrence of any dangerous or undesirable conditions at the surface, as when a ship strikes the platform of a marine type installation, or bombs, or fire or other catastrophes occur at the well head, which are sensed by sensing means at the surface as set forth in the patent to Sizer, US. Pat. No., Re. 26,149. The control fluid in the control fluid line L will then be released and the valve permitted to move to closed position in the manner set forth in the patent to Fredd, US. Pat. No. 3,007,669, or Sizer, Re. 26,149.

However, in any installation, a slight leak can occur between the flange connections of the several elements or components of the Christmas tree X, as a result of the deterioration or damage of the seal rings R, R2, R3, R4, etc., or in the event of a flre which weakens the bolts holding the flanges together and permits the same to stretch and the flanges to separate to permit well fluids to flow outwardly between the flanges past the seal rings. In such event, the volume of flow of the fluids from the well through the tubing string may not be sufficient to cause the valve V to close and the sensing mechanism at the surface may not sense such a condition to relieve the pressure acting on the sub-surface safety valve to cause the valve to close.

To provide means for positively closing off the flow of fluids through the tubing string from the producing formation to the surface through the Christmas tree in the event the flanges separate or there is other damage to the Christmas tree resulting in a slight lateral leak, which is the type that may be ignited and burn with a small but damaging flame, that the method, the apparatus and system of this invention is directed. Also, this method, and the apparatus and system used in carrying out the method, provide for an early and prompt closing off of flow through the conductor upon the occurrence of a fire or heat applied to the Christmas tree, as wellas leaks between the flanges of the various components of the Christmas tree, and other undesirable or unsafe conditions.

Tubing hangers are currently in use which provided with internal annular locking and sealing recesses and surfaces for receiving and anchoring a plugging tool in place in the bore of the hanger sealing with the hanger or the upper end of the tubing string immediately therebelow to close off the bore of the tubing string and prevent flow upwardly therethrough. These plugs, however, must be inserted and removed each time it is desired to so close off flow. Tubing hangers and plugging tools of the type just described are illustrated in the patent to John V. Fredd, U.S. Pat. No. Re. 25,289. Also, when the plug is in place, the well cannot be produced until the plug is removed.

The method of this invention is directed toward providing an automatically operable remotely controlled flow controlling safety valve disposed in the tubing hanger or the tubing head within the upper end of the tubing string for closing off flow through the tubing string. This valve installation and the method of controlling flow of fluids from the well through the tubing string without completely re-working the well is an important feature of this invention.

In carrying out the method and effecting the installation of the system for controlling the well, the well head plug J is installed in the tubing hanger S in the manner set forth in the aforesaid patent to Fredd, U.S. Pat. No. Re. 25,289, and the Christmas tree above the tubing head H is disconnected and lifted, as shown in FIG. 2, to permit installation of an adaptor or spool D, as shown in FIG. 3. Theadaptor spool has flanges at its ends by means of which it is connected to the flange at the upper end of the tubing head H and to the lower end of the master valve at the lower end of the Christmas tree X, as shown in FIG. 3. The adaptor spool is provided with a control fluid flow conduit and connection by means of which control fluid may be directed into the bore of the adaptor and into the upper end of the bore of the tubing hanger or support S, as will hereinafter be more fully set forth. In the seal ring R3 is disposed between the lower end of the adaptor D and the upper end of the tubing head, while a seal ring R5 is disposed between the flanges at the upper end of the adaptor D and the lower end of the master valve M of the Christmas tree X. After the adaptor has been connected between the tubing head and the Christmas tree, and a control fluid line L2 has been connected to the flow passage and outlet connection Q, as shown in FIG. 4, with a valve N2 therein connected therein for controlling fluid from a control fluid manifold unit U, the closure plug or well head plug J is removed from its position in the tubing hanger S, and a flow controlling safety valve V2 is installed therein, as shown in FIG. 4, the valve being locked in place by means of a locking and sealing mandrel assembly I of the type illustrated in detail in FIGS. 8-A and 8-B.

The locking and sealing mandrel assembly I has sealing members that engage the bore wall of the adaptor D above the flange and the inner end of the control fluid inlet Q and the lower packing members which seal between the mandrel and the bore wall of the tubing hanger S below the locking recesses in the bore of said tubing hanger, whereby control fluid from the line L2 passing through the inlet passage Q is directed to the flow controlling safety valve V2 to control actuation thereof in the manner set out in the patent to Fredd, US. Pat. No. 3,007,669, or in the application for patent to William W. Dollison, Ser. No. 786,149, filed Dec. 23, 1968 now U.S. Pat. No. 3,583,442, issued June 8, 1971. The details of construction of the locking and sealing mandrel assembly and the valve V2 will be described more fully hereinafter in connection with FIGS. 8-A and 8-B. However, the valve V2 is shown in open condition in FIG. 4 and in closed position in FIG. 5.

Control fluid from the control line L2 enters into the bore of the adaptor D between the lower flange of the adaptor and the upper flange of the tubing head A and passes downwardly in the annular space between the locking and sealing mandrel to the valve V2 where it acts on the valve to move the same to the open position shown in FIG. 4 to permit well fluids to flow upwardly from the well with the valve anchored in place in the tubing head in the manner illustrated. However, should the pressure of the control fluid in the annular space between the packing members of the locking and sealing mandrel and the bore wall of the adaptor D and tubing head H within the seal ring R3 be released or reduced sufficiently, the valve will automatically move to the closed position as shown in FIG. 5 to close off all flow through the tubing string below the hanger S. Such a condition might arise, as shown in FIG. 5, by stretching of the means holding the lower flange of the adaptor D connected with the upper flange of the tubing head I-I, causing slight separation of the flanges, and so permit the control fluid confined within the inner diameter of the seal ring R3 to escape outwardly and reduce or release all pressure in such annular space and so permit the valve V2 to close. The connecting bolts might have been caused to stretch by heat or by over tension or wear or the like, or the seal ring R3 may have been damaged as a result of corrosion or impacts, dents or the like, which would cause the same to leak and release the control fluid to cause the valve to close. Such a small leak would not ordinarily be sufficient to cause the down-hole safety valve flow controlling safety valve V to close in the usual installation, because the sensing members connected with the control line L at the surface would not ordinarily sense such a leak to release the pressure of the control fluid in the line L to permit the valve to close.

Also, such a lateral leak between the flanges of the connected components of the Christmas tree may be sufficiently small enough in volume not to cause actuation of the down-hole safety valve V, but when the leaking fuel is ignited it would cause serious damage to the platform or surrounding well, which could result in further damage to the Christmas tree connections and turning the well loose to permit uncontrolled flow. Therefore, the well head safety valve V2 provides for immediate and complete closure of the flow passage from the producing formation through the tubing string T in the event of loss of pressure of the control fluid present in the control line L2 for any reason, whether by leakage or any other condition sensed by the manifold U controlling the supply of control fluid to the well head safety valve V2.

Various types of monitoring equipment may be provided in the manifold U for sensing various conditions which would release the control fluid pressure in the line L2 to permit the valve V2 to close upon the development of any undesired condition for which the sensors or monitoring devices are provided. In addition, upon the occurrence of a leak in the connections between the tubing head H and the Christmas tree elements or components thereabove, which will release the control fluid pressure present in chamber formed in the annular space between the mandrel of the locking and sealing device I and the bore wall of the adaptor D and the tubing head H, such a leak will automatically and promptly relieve the control fluid pressure acting on the tubing head or hanger safety valve V2 and cause the same to be moved to closed position to shut off flow through the tubing string and prevent further escape of well fluids.

The pressure of the control fluid is ordinarily created and maintained by means ofa small pump which builds up and acts to provide a constant source of pressure to maintain the safety valve in the open position even though there may be a very small leak in the control fluid lines or in the chamber of the system. Thus, any leak reducing or completely relieving the control fluid pressure acting on the valve V2, downstream of a small restrictive orifice in the control fluid line L2 between the manifold and the adaptor D, will prevent the pump from completely replacing the fluid and permit the valve to close, in which event the pump is automatically shut off by a pressure valve or throttle or switch controlling the supply of fuel or power to the pump. As an alternative, the reservoir of control fluid at the pump may be very small so that it would be exhausted upon the occurrence of a small leak, and the valve will then close upon the exhausting of the pressure. The pump will be cut off in either event, upon exhausting of the fluid from the reservoir or the closing of the valve.

Manifestly, the down-hole safety valve V may be connected in the same manifold with the tubing head safety valve V2, if desired. Such a manifold arrange ment is illustrated in FIG. 6, wherein the control fluid manifold U2 is connected by a line L3 wherein the control unit U is connected by means of a control fluid line L3 with the control fluid line L leading to the downhole safety valve and with the control fluid line L2 leading to the tubing head safety valve V2. A venting valve N3 is also connected to the line L3, while the valve N is connected in the control fluid L controlling the supply of control fluid under pressure through the line L to the down-hole safety valve V, in the same manner as the valve N2 controls the supply of control fluid pressure to the line L2 to the tubing head safety valve V2. With the valves N and N2 open permitting application of the control fluid pressure to the two safety valves V and V2, any leak in the system which reduces or relieves the control fluid pressure acting on the valve would cause the valves to be moved to closed position shutting off flow through the tubing string. Also, the valve N3 may be opened to reduce the control fluid pressure acting on the safety valves to cause them to close, if desired.

Further, it is believed apparent that the seal ring R5 between the upper flange of the adaptor D and the lower flange of the master valve M may be of the type shown in FIG. 7-A, having a vertical flow passage formed therein and connecting the ring grooves of the flanges of the Christmas tree components between which it is positioned to permit control fluid pressure to be supplied to the ring grooves above and below the seal ring R5, whereby any separation of the flanges will cause leakage of the control fluid through the grooves in the flanges above or below the ring R5 and reduce or completely relieve control fluid pressure in the manifold to cause actuation of the tubing head safety valve V2.

Such a well head installation is shown in FIG. 7 wherein the control fluid manifold U is connected by means of the control fluid line L3 to the control line L2 and the valve N2 leading to the surface tubing head safety valve V2, and may be also connected by means the control fluid line L and the valve N to the downhole safety valve V in the manner illustrated in FIG. 6. Similarly, the line L3 may be connected to a line L4 and valve N4 leading to the seal ring R5. Thus, if the pressure within the grooves of the flanges in which the seal ring R5 is disposed is reduced or relieved, the control fluid pressure acting on the safety valves V and V2 will be reduced or relieved and cause the valves to close immediately and shut off flow through the tubing string.

The seal ring R5, as shown in FIG. 7-A, comprises an annular metal ring 10 having convex upper and lower annular surfaces 11 and 12, respectively, adapted to fit in the tapered grooves 13 and 14, respectively, of the flanges of the components of the Christmas tree between which the rings are disposed in sealing position. A flexible V-type packing ring or sealing ring 15 is suitably bonded or affixed to the inner annular periphery of the ring 10 and is adapted to engage the opposed surfaces of the flange 16 and 17 of the Christmas tree components to seal therebetween to prevent escape of well fluids in the event the flanges become separated as by elongation of the bolts for any reason. Also, this seal ring 15 will prevent contact of the well fluids with the metal seal ring 10 to reduce or prevent corrosion of the ring by the chemicals present in the well fluids. The control fluid line L4 from the valve N4 is connected to the outer periphery of the seal ring body 10 by soldering or brazing or otherwise securing the inner end of the line L4 in a radial aperture 18 formed in the outer medial portion of the ring and communicating with the vertical bore 19 therein. Control fluid pressure thus will be confined in the annular space in the grooves 13 and 14 and any reduction in pressure in either of the annular areas will reduce the pressure in the other and reduce or relieve the pressure present in the control line L4 to permit the tubing head safety valve V2 to close. Also, if the down-hole safety valve V is connected to the line L with the manifold, the release of pressure in the grooves 13 and 14 will cause the down-hole valve to close as well.

As shown in FIG. 7, a ring R5 such as is shown in FIG. 7-A may be disposed between the flanges of the master valve and the flow cross, and a control fluid line L5 connected thereto after passing through the valve N5. Similarly, a valve ring R5 may be disposed between any other component of the Christmas tree and connected by means of a control fluid line L6 having a valve N6 therein, if desired. Thus, any separation of the flanges or connections of the components of the Christmas tree for any reason, whether by elongation, heat or by deterioration of the seal provided by the seal rings R5, R5, or any other seal ring between two components, will permit the pressure of the control fluid-to be reduced or relieved and the valves to be closed upon such occurrence.

A modified form of sensing device adapted to be disposed between the adjacent flanges of connected components of the Christmas tree is shown in FIGS. 9 and 9-A, wherein a rectangular body member 20 having an enlarged flange 21 on its outer end is provided with a control fluid passage 22 extending inwardly centrally of said body from a threaded inlet opening 23 in the flange 21 to which the control fluid line may be connected. The lower surface 25 of the body is upwardly and inwardly inclined and engages the inclined surface 26 of a lower closure member 27 which closes the inlet or bore 22 of the body 20. The two members are pressed together firmly in a wedge fit by driving or pressing the body member 20 inwardly along the inclined upper surface 26 of the closure member 27 between the upper flange 28 and the lower flange 29 of two interconnected components of the Christmas tree of the well. The inclined surfaces provide a tight seal closing the inner end of the bore 22 when the flanges are clamped together and the members are driven into position therebetween. Should any spreading occur between the flanges 28 and 29, the inclined surfaces will quickly separate and permit the control fluid in the bore 22 to escape and release control fluid pressure to actuate the safety valve V or V2, or both, with which the control fluid line L4 is connected.

The wedge closure member 27 may be formed of a low temperature melting or fusible metal, such as Cerrometal or the like, which when subjected to a predetermined temperature will melt and flow to release the control fluid present in the bore 22 of the body 20 of the sensor 19. Thus, the sensor 19 is not only responsive to separating movement of the flanges 28 and 29, but will likewise sense elevated temperatures such as may result from a fire adjacent the Christmas tree, to cause the safety valves V or V2 to close upon the occurrence of such an event.

A plurality of the sensor members 19 will be positioned at circumferentially spaced points around outside the seal ring R between the two adjacent flanges, so that any movement of the flanges which causes separation will actuate one or more of the sensors 19 to release the control fluid confined in the bore 22 thereof. The control fluid line L4 will be connected to each of the sensors 19 as shown in FIG. 11, and the sensors will be disposed between the usual bolts 30 connecting the flanges. It will, therefore, be seen that the sensing members 19 will release control fluid present in the bores 22 thereof upon separation of the flanges 28 and 29 to cause actuation of the valves V and V2 by releasing the pressure present in the control fluid line L4 connected to the control fluid lines L and L2 leading to the valves.

A further sensing device 35 is shown in FIGS. and 10-A in which a rectangular housing 36 of dielectric or non-conductive material is disposed between the flanges 37 and 38 and confined tightly therebetween, being positioned at circumferentially spaced points around the seal ring between the flanges in the same manner as the device of FIGS. 9 and 9-A, as shown in FIG. 11. Within the housing 36 is a normally biased open electrical microswitch 40 having a fixed base conductor 41 provided with a contact point 42 and an elongate leaf spring conductor arm 45 mounted at its inner end between insulator spacers 43 and 44 and having a contact46 on its outer end portion disposed to engage the contact 42 of the stationary arm'or conductor. The leaf spring conductor 45 normally biases the contact 46 away from the contact 42 to open the switch. A pressure button or plunger 47, having a head 48 and a reduced body 48a, is movable in an aperture 49 in the housing or case 36 and is pressed upwardly by the lower flange 38 to the position shown in FIG. 10, wherein the leaf spring contact arm 45 is moved toward the stationary conductor 41 to bring the contacts 42 and 46 into engagement and establish a circuit between the conductors. The length of the button or plunger 47 is such that the contacts are moved into engagement when the flanges are drawn together in the usual manner. However, should the flanges separate in the manner already described for any reason, the leaf spring conductor 45 will move the lower contact 46 away from the contact 42 and break the circuit between the conductors 41 and 45. The ends of the conductors 41 and 45 adjacent the insulating spacers or separators 43 and 44 are connected to suitable electrical conductor wires 48 and 49, respectively, leading to a source of electrical power and to a solenoid valve N3A or the like connected to the control manifold U. When the contacts are separated, the circuit is broken and the solenoid valve is permitted to move to release the control fluid from the control fluid lines L and L2 and permit the safety valves V and V2 to close. The solenoid valve is deenergized when the contacts are separated and the valve is actuated in the usual manner to open the valve and release the control fluid pressure. The electrical sensors 35 may be disposed between any two adjacent flanges of any two adjacent components of the Christmas tree on the well to sense the separation of the flanges and cause the safety valves to close.

The button 47 may have a low temperature fusible body 48a and a dielectric head 48, whereby at a predetermined temperature the body 48a will melt and permit the switch to open.

Details of the tubing head H with the hanger or sup port S secured therein and supporting the tubing string T, and having the adaptor D connected thereto is shown in FIG. 8-A. Also shown in detail is the construction of the tubing head flow controlling safety valve V2 and the locking and sealing mandrel I. The lower flange of the master valve M is shown connected to the upper flange of the adaptor or spool D, while the tubing head is connected at its lower end to the upper end of the exit bushing B.

The tubing hanger or support S is shown as threaded into the lower end of the bore of the tubing head I-[ in the usual manner and consists of an elongate tubular body 50 having a downwardly and outwardly inclined seating surface 51 intermediate its ends spaced above the external annular threaded enlarged lower portion 52 of said body. A seal ring 53 is provided in the sealing surface 51 for sealing between the support body and the tubing head H. The upper reduced portion of the body extends upwardly in the reduced upper portion of the bore 55 of the tubing head in the usual manner. The lower portion of the bore 56 of the hanger is enlarged in diameter and provided with internal annular threads 57 by means of which the upper end of the tubing string T is threadedly connected to the hanger for suspension from the tubing head. The upper portion of the bore 56 of the hanger is provided with a pair of internal annular locking and seating recesses 58 above a sealing surface extending between said recesses and the threaded portion 56 of the hanger. This hanger is similar to that shown in the patent to John V. Fredd, Re. 25,289, and the hanger is adapted to receive a well head plug J similar to the plug illustrated in that Fredd patent for closing the upper end of the bore of the tubing against flow therethrough in the manner already described.

The adaptor spool member D comprises a tubular body 60 having a substantially cylindrical bore 61 which is reduced at its lower portion to provide a sealing surface 62 therein. The lower flange 63 of the adaptor is connected to the upper flange 64 of the tubing head H, and the sealing ring R3 or R is adapted to be disposed in the sealing grooves formed in the opposing faces of the flanges. The upper flange 65 of the adaptor member is connected to the lower flange 66 of the master valve at the lower end of the Christmas tree and a suitable sealing ring R5 is disposed in the annular grooves formed in the opposed faces of the flanges for sealing therebetween. The flanges 65 and 66 and the flanges 63 and 64 are drawn together by bolts (not shown) in the usual manner to engage the sealing rings R3 and R5 to seal between the components of the Christmas tree and to provide a continuous passageway through the Christmas tree connected in flow communication with the upper end of the tubing head H. The inlet opening and passage Q in the adaptor D consists of an elongate passage 70 opening at its lower end to the lower face of the flange 63 within the sealing ring groove in the lower face of such flange in which the sealing ring R3 is disposed. The upper end of the passageway communicates with an enlarged opening 71 having an enlarged threaded outer portion 72 formed therein in a boss 73 on the exterior of the adaptor, by means of which the control line L2 may be connected to said adaptor.

The tubing head flow controlling safety valve V2 is similar to that illustrated in the patent application of William W. Dollison, Ser. No. 786,149, filed Dec. 23, 1968, now US. Pat. No. 3,583,442, issued June 8, 1971, and comprises an elongate tubular housing 80 having an internal thread in its upper end by means of which it is connected to the lower end of the mandrel 90 of the locking and sealing device 1. The lower end of the bore of the tubular housing 80 is reduced in diameter to provide an upwardly facing shoulder 81 engaged by the lower end of a helical coil spring 82. An elongate tubular valve piston and seat member 85 is slidable longitudinally in the bore of the housing 80 and has a piston member 86 near its upper end provided with an O-ring or other suitable sealing ring 87 externally thereon for sealing between the piston and the bore wall of the housing. The spring 82 bears against the lower surface of the piston 86 and biases the member 85 upwardly in the housing. An external annular enlarged closure head member 88 is formed on the lower end of the tubular seat and piston sleeve 85 and has a beveled seat 8821 at its upper end disposed to engage a complementary beveled stop surface or seat 88a at the lower end of the housing 80 when the valve is moved to closed position. An equalizing port 88b is formed in the wall of the sleeve 85 above the seat 88a to permit easy opening of the valve in the manner set forth in the aforesaid patent application. The sleeve 85 below the closure head 88 is reduced in diameter to provide an external annular groove 89 above an external annular flange and seat member 100 at the lower end of said sleeve 85 against which the ball closure member 110 of the valve seats. A pair of connecting links 105 have hooks at their upper ends engaged in the external annular recess 89 and inwardly projecting pins 102 engaging in complementary recesses in the ball closure member 101, whereby the ball closure member is moved with the sleeve 85. The ball will pivot about the pins 102 engaged in the recesses in the ball, and rotation of the ball is effected by means of pins 103 on opposite sides of the ball engaged in angularly disposed slots 104 formed in the outer periphery of the ball. The pins 103 are carried by a slidable sleeve 106 mounted in the enlarged lower portion of the bore ofa valve cage 107 which is provided with internal threads 108 at its upper end by means of which it is connected to the lower end of the housing 80. A thimble 109 is threaded into the lower internally threaded end of the bore of the cage 107 and provides a downward stop for the ball closure member for positioning the transverse flow passage 110a of the ball closure member in alignment with the longitudinal flow passage 112 in the bushing. The upper end of the bushing also serves as a stop for the sleeve 106. When the flow passage 110a of the ball valve closure 110 is in alignment with the flow passage 112 in the bushing it is also in alignment with the longitudinal flow passage or bore 85a in the elongate tubular sleeve 85, whereby fluids may flow through the ball closure member upwardly through the sleeve and then upwardly through the locking and sealing device I. A stabilizing pin 105 is also provided in the sleeve 106 to guide the movement of the links 101 on the opposite sides of the ball closure for guiding the same in their vertical movement and to assure rotation of the ball closure member 1 10.

When the piston 86 is moved downwardly by fluid pressure applied to the upper end thereof against the force of the spring 82, the tubular sleeve 85 is moved downwardly and the ball is rotated to the open position shown in FIG. 8-B. When the pressure acting on the piston 86 is reduced or relieved, the spring 82 will move the tubular sleeve upwardly and lift the ball closure member 110 to cause rotation thereof to the closed position as shown in FIG. 5.

The anchoring and sealing assembly 1 comprises the elongate tubular mandrel 90 having an external annular packing assembly 91 confined thereon between the upper end of the valve housing and an external annular flange 92 formed on the mandrel. An O-ring or other seal member 93 seals between the locking and sealing mandrel 90 and the upper end of the housing 80 of the valve. Likewise, the upper reduced end 850 of the tubular piston sleeve has a sliding fit in the lower portion of the bore a of the mandrel 90 and an internal annular sealing ring 94 in the bore of the mandrel seals between the valve sleeve and the mandrel to provide a control fluid pressure chamber in the upper portion of the bore of the valve housing below the lower end of the mandrel by means of which control fluid may be confined to act on the piston 86. Control fluid is directed into the chamber 95 through one or more longitudinally extending flow passages 96 formed in the mandrel and extending from the lower end thereof to the upwardly facing stop shoulder 97 against which the locking dogs are confined and which limits downward movement of an elongate expander and locking sleeve 127 on the upper reduced portion of the mandrel above said shoulder.

The locking dogs 120 are disposed in radial windows 122 formed in a dog carrier sleeve 123 threaded at its lower end onto the upper end of the large lower portion of the mandrel below the shoulder 97 and above the flange 92. The lower ends of the windows 122 are in substantial alignment with the upwardly facing shoulder 97 and provide a further support for the locking dogs at that point. Suitable lateral flanges (not shown) on the dogs limit outward movement of the dogs from the sleeve and suitable springs (not shown) bias the dogs outwardly of the windows to a position at which the downwardly facing abrupt stop shoulder 125 on the dogs will engage the upwardly facing stop shoulder 58a in the locking and positioning recesses or grooves 58 of the tubing hanger. The exterior faces of the dogs conform to and are complementary with the configuration of the locking and stopping recesses or grooves 58. The lower portion of the expander and locking sleeve 127 is slidable on the upper reduced portion of the locking and sealing mandrel 90 and within the enlarged lower portion of the bore of the dog carrier sleeve. An external annular packing assembly 130 is mounted on the upper portion of the dog carrier sleeve confined thereon between an upwardly facing shoulder 131 and the downwardly facing lower end of a retaining ring nut 132 threaded onto the upper end of the sleeve. An internal seal ring 133 is disposed in a suitable annular groove in the bore of the expander sleeve 127 and seals between the expander sleeve and the exterior of the reduced upper neck portion 98 of the mandrel 90. A retaining nut 99 is threaded or silver soldered or otherwise suitably secured to the upper end of the neck 98 of the mandrel and the upper portion of the bore of the expander sleeve 127 is enlarged to slide along the outer surface of the nut 99 at the upper end of the mandrel. The upper portion of the expander sleeve is formed with longitudinal slots or slits 128 providing a plurality of upwardly extending resilient fingers 129 on the upper end of the expander sleeve which are contractible to permit the enlarged external flange shoulders 129a to enter the reduced lower end of the bore of the detent locking sleeve 150 past the internal annular stop flange 155 at the lower end of the sleeve for assembly of the parts together. A radial aperture is formed in each of the fingers and a detent locking ball member 135 is disposed in each of the openings and is adapted to engage the downwardly facing beveled shoulder 99a at the lower end of the nut 99 to lock the locking sleeve 127 in its lower position.

An internal annular seal ring 137 is disposed in a suitable internal annular groove in the bore of the dog carrier sleeve below the external packing assembly 130 and seals between the dog carrier sleeve and the external surface of the expander sleeve .127, while the ring 133 disposed in a suitable internal annular groove in the expander sleeve 127 seals between mandrel neck 98 and the base of the expander sleeve, whereby fluid pressure within the bore of the adaptor member D and end of the external bosses or flanges 1240 on the fingers 129 at the upper end of the expander sleeve to press the locking detent ball 135 inwardly of the apertures 134 below the shoulder 99a at the lower end of the locking nut to hold the expander sleeve in the lower position in which the dogs are locked in expanded locking position in the recesses 58. Near the lower portion of the enlarged lower bore of the detent locking sleeve is formed an internal annular recess which is disposed to be aligned with the detent balls 135 to permit the balls to move outwardly in the apertures 134 to pass the shoulder at the lower end of the nut 99 to permit retraction of the expander sleeve upwardly from engagement with the locking dogs. The internal annular flange 155 at the lower end of the detent locking sleeve engages the downwardly facing shoulder at the lower end of the bosses 129a on the fingers 129 at the upper end of the expander sleeve to lift the expander sleeve when the detent locking sleeve is moved upwardly. A fishing tool recess 156 is formed in the upper end of the bore of the detent locking sleeve 150 for engagement by suitable retrieving tool by means of which the sleeve may be lifted to lift the locking sleeve and release the dogs to permit the tool to be retrieved from its position in the tubing hanger.

To install the device the locking sleeve is secured by means of a shear pin 160 to the dog carrier sleeve 123. The shear pin extends through aligned apertures 161 and 162 in the dog carrier sleeve and expander sleeve, respectively, and when so disposed holds the expander sleeve in the upper position out of engagement with the locking dogs. When the anchoring and sealing device 1 has been lowered through the Christmas tree until the downwardly facing stop shoulder on the dogs 120 engages the upwardly facing stop shoulder 58a in the locking recess grooves 58, downward force applied to the locking detent sleeve 150 moves the same downwardly to move the shoulder 153 at the lower end of the internal flange provided by the reduced central bore 154 into engagement with the upper ends of the fingers 129 to force the expander sleeve downwardly and shear the shear pin 160. Further downward force applied to the detent locking sleeve will then move the expander sleeve downwardly between the dogs to hold the same locked in expanded holding position. When downward movement of the expander sleeve has been limited by engagement of the lower end thereof with the upwardly facing shoulder 97 on the mandrel, the balls are disposed beneath the downwardly facing shoulder 99a on the head 99 at the upper end of the mandrel neck and the detent locking sleeve may move downwardly to move the locking surface 152 provided by the enlarged bore below the shoulder 153 into engagement with the balls to move the balls inwardly below the downwardly facing shoulder 99a and lock the expander sleeve in its lower locking position. Thus, the anchoring and sealing device is disposed in anchored sealed position within the bore of the tubing hanger S and the bore of the adaptor D. The upper packing 130 will seal against the sealing surface 62 in the adaptor and the lower packing 191 will seal against the sealing surface 59 in the bore of the tubing hanger.

Control fluid passing inwardly through the passageway 70 into the annular space within the seal ring R3 and in the bore of the adaptor D and the tubing head H will be confined between the upper packing 130 and the lower packing 91 exteriorly of the mandrel 90 and will pass downwardly through the elongate longitudinal passage 96 in the mandrel into the chamber 95, where it will act on the piston 86 to move the valve seat and piston tube 85 downwardly to move the ball closure member 110 of the valve to open position against the force of the spring 82.

It will be noted that the upper end of the locking and sealing assembly I is disposed below the master valve M so as not to interfere with the operation thereof. It is also preferable that the adaptor spool or member D be of such longitudinal dimensions that should the anchoring device and valve member V2 be disposed in the tubing hanger with the detent locking sleeve is in its upper position, the upper end of such sleeve is nevertheless still disposed below the closure member of the master valve and will not interfere with operation of the master valve to close off flow therethrough.

When the valve V2 is closed, the bore of the tubing is closed at the tubing hanger S and any leakage in the connections between the components of the well head Christmas tree thereabove will be terminated. The structures described are those effective to carry out the method by use in the system of the invention.

A slightly modified form of means for supporting the tubing head valve in the tubing hanger is shown in FIG. 12, wherein a slightly different form of tubing hanger S1 is disposed in modified form of tubing head H1. The hanger S1 is commonly known as the bollweavel type hanger and has an enlarged external downwardly tapered upper end portion 202 which is designed to seat in a downwardly tapered bore 203 in the tubing head. Seal rings 200 are disposed in external annular grooves 201 formed in the tapered surface 202 of the hanger S1 and seal between the hanger and the tapered bore 203 of the tubing head H2. Suitable hold down screws 207 are threaded through the flange at the upper end of the tubing head and engage an inwardly inclined locking surface 208 at the upper end of the external annular flange or head of the hanger. A packing gland and nut 205 seals around each of the hold down screws. The bore of the hanger is enlarged at its lower end and threaded as at 206 to receive the upper end of the tubing string T in the usual manner. The central portion of the bore of the hanger is reduced in diameter and provided with interval threads 209 having a modified downwardly facing buttress shape, each having a downwardly facing stop shoulder inclined inwardly and upwardly and a longer inclined downwardly and inwardly lower stop surface, for receiving a complementary externally threaded sleeve 210 having modified buttress threads 211 thereon which may be rotatably threaded into said interval buttress threads 209 and secured in place thereby. The sleeve 210 has O-ring seal members 212 disposed in external annular recesses 213 above the threads which seal in the bore 214 of the hanger above the threads in said bore. The upper portion of the bore of the hanger is enlarged and provided with internal threads 215 forengagement by handling pipe or the like in the usual manner.

The locking sleeve 210 has an internal annular thread in the lower portion of its bore into which the externally threaded upper end 180a of the housing 180 of the valve V3 is threaded. An internal annular seal ring 113 is disposed in a suitable internal annular groove in the sleeve below the threads for sealing between the sleeve and the housing. The locking sleeve 210 forms an upper continuation of the valve housing and the upper portion of its bore is enlarged to provide a cylinder in which the piston 286 of the tubular valve seat and piston sleeve 285 of the valve is slidable. The external annular seal ring 287 in the piston seals between the piston and the bore wall of the cylinder, and the upper reduced end 2850 of the sleeve 285 is slidable in a sub 218 connected to the upper end of the sleeve 210 by a reduced externally threaded depending portion 218a which is threaded into internally threaded upper end of the locking sleeve. A locking screw 220 is threaded through the locking sleeve and into a recess in the sub to hold the same securely locked together with the inclined seating surfaces 221 and 222 on the locking sleeve and the sub, respectively, in sealing engagement with each other. An internal annular seal ring 223 is disposed in a suitable internal annular groove 224 in the base of the reduced lower end of the sub and seals between the sub and the reduced upper end or neck 285c of the tubular valve seat and piston member 285. The O-ring may be confined between non-extrusion rings of the usual type, if desired. The locking screw permits rotation of the sub 218 and the locking sleeve 210 to effect rotation of the buttress threads on the exterior of the locking sleeve into the corresponding interval buttress threads 209 in the bore of the tubing hanger.

A connector and packing bushing 230 is threaded into the upper enlarged upper portion of the bore of the sub 218 and a locking screw 231 is threaded through the sub and engages the packing bushing 230 to prevent disengagement of the threads and to permit rotation of the members in the manner already set forth. An external annular flange 233 at the upper end of the bushing 230 clamps or confines an external seal assembly 235 on the bushing between the upper end of the sub 218 and the shoulder 234 at the lower end of the flange 233.

The bore of the bushing is internally threaded at 241 to provide means for connecting handling tubing or rods thereto for rotation of the locking sleeve to engage the buttress threads and the corresponding threads in the hanger. A pair of diametrically opposed slots 240 are provided in the upper end of the bushing for engagement with a key pin carried by the rod, by means of which the device is lowered into and locked in place in the tubing hanger.

The buttress threads in the bore of the tubing hanger and the external buttress threads on the locking sleeve are left hand turn so that when the device is to be removed from the tubing hanger the usual threaded rod or tubing may be inserted into the threads 241 at the upper end of the bushing 230, which are right hand threads, and the tubing or rods rotated in a right hand or clockwise direction to cause the disengagement of the buttress threads by such rotation.

The external seal member 235 seals against a sealing surface 250 formed in the bore of a spacer flange 251, connected in the same manner as the adaptor sleeve or spool D previously described between the upper flange at the upper end of the tubing head H1 and the lower flange at the lower end of the Christmas tree, usually the lower flange of the master valve M.

An angular flow passage 252 is formed in the flange, extending horizontally inwardly from the outer periphery of the flange and upwardly from the lower surface thereof within the sealing ring groove 253 in such surface in which the sealing ring R3 is disposed. The outer end of the horizontal portion of the passage is enlarged at 254 and threaded to provide means for connection of the control fluid line L2 thereto for conducting control fluid into the bore of the tubing head above the hanger.

The locking sleeve has a lateral flow passage 210a formed in the wall thereof communicating with a cylinder or chamber 295 formed in the bore of the sleeve above the piston 286 whereby the control fluid from the passage 252 will act on the upper end of the piston 286 to bias the elongate valve seat and piston sleeve 285 downwardly against the force of the spring 282 to open the valve therebelow connected with said sleeve.

The operation of the valve is similar to that already described and the spacer flange or spacer member 251 corresponds in function to the adaptor member D of the forms previously described. Otherwise, the valve assembly V3 is held in place by means of the buttress threaded connection between the externally threaded sleeve 210 and the internally threaded bore of the tubing hanger S1.

In FIG. 13, a multiple producing zone of flow string well installation is shown wherein two strings of tubing are disposed in the casing and communicate with a lower zone Z1 below a lower packer P1 and an upper zone Z2 communicating with the casing between the lower packer P1 and an upper packer P2. The tubing string T1 communicates with the lower zone below the lower packer and the tubing string T2 communicates with the upper zone between the packer P1 and the packer P2. Down-hole control valves V and V4, which correspond to the down-hole valve previously described, are connected in the tubing strings T1 and T2, respectively, and are operated in the same manner.

An exit bushing or fixture B1 is connected to the casing head Al and control fluid lines L and L1 extend downwardly through suitable packing glands G in the exit bushing B1 to the down-hole valves for conducting control fluid to such valves for actuating the same in the manner already described. The control fluid manifold and valves of this Figure are identical to those of FIG. 4.

The tubing strings T1 and T2 are connected at their upper ends to separate hangers S3 and S4, respectively, in a multiple string tubing head H4. Each of the tubing strings communicate with separate flow passages through the adaptor spool D2 and the flow courses are separated from each other by suitable annular seal rings R7, R8, R9 and R10. The master valves M1 are connected to the upper end of the adaptor in the usual manner and the Christmas tree includes the usual dual string cross X1 and flow wings and valves.

A tubing head flow controlling safety valve V2 is disposed in each of the hangers S3 and S4, the safety valve being identical to that shown in FIGS. 8-A and 8- B and anchored in place in the hangers in the same manner. Control'fluid is directed into each of the flow passages in which the valves are anchored in sealing position in the same manner as in the device of FIG. 4 and acts on each of the valves identically with that previously described. The seal rings R7, R8, R9 and R10, prevent communication of the control fluid in one of the flow passages with that in the other so that each of the valves is separately controlled if desired.

Control fluid manifolds U5 and U6 are connected to the control fluid inlets Q5 and Q6, respectively, of the adaptor spool D2 for supplying control fluid to control actuation of the valves. If desired the control fluid manifolds U5 and U6 may be connected to the control unit manifolds U by a suitable connecting line L10 so that the down-hole valves and the tubing head safety valves are connected together in the same manner as were the valves of FIGS. 6 and 7. Also, it is believed readily apparent that sensing devices may be disposed between the flanges of the connected components of the Christmas tree of this system as well as those previously described.

In FIG. 14 a modified form of tubing hanger is shown, wherein the body 350 is threaded as at 352 into the bore of a tubing head H5. The tubing head has a lateral control fluid inlet passage 370 formed in its wall which has its outer portion enlarged and threaded to receive the control fluid line L11 from the flow control fluid unit U7. External annular seal rings 351 and 353 are mounted in suitable external annular grooves on the hanger body 350 and seal between the hanger and the bore wall of the tubing head H5 above and below the lateral inlet 370. The bore 355 of the hanger has internal annular locking and stop grooves 358 formed therein for anchoring and locking and sealing mandrel of a flow control valve V2 (not shown) in place in the hanger.

Below the locking and locating grooves 358 the bore of the hanger is slightly reduced in diameter to provide upper and lower sealing surfaces 360 and 361, respectively, above and below an internal annular recess 362 formed in the bore between said sealing surfaces. A lateral inlet port 365 is formed in the wall of the hanger communicating with the internal annular recess 362 in the bore of the hanger and with the inlet port 370 in the tubing head H5 for conducting control fluid pressure into said groove for controlling actuation of the safety valve supported therein.

In this installation the anchoring and positioning grooves and keys are located above the sealing surfaces and a slightly modified form of tubing head and hanger are utilized. Otherwise the device functions in the same manner in carrying out the method and system of the invention.

The upper flange 364 of the tubing head H5 has a radially inwardly extending conduit 366 formed therein having its inner end portion 367 inclined upwardly to communicate with the annular ring groove 368 in the upper face of the flange in which the seal ring R55 is seated. The seal ring R55 is similar to that illustrated in FIG. 7-A. However, only the vertical bore or passage 309 is formed in the ring body 310, and the inner end 367 of the flow passage 366 communicates with the bottom of the annular recess 368 in which the ring R55 is disposed. The ring R55 does not have a lateral port communicating with the control fluid line, but instead the passageway 366 communicates with the annular groove 368 in which the ring is disposed, and through the vertical passage 309 with the groove 369 in the lower face of the lower flange 66 of the master valve. In

this form of the device, as in the device of FIG. 7-A, any leakage between the flanges and the seal ring R55 will reduce the pressure of the control fluid present in the port passage 366 and, acting through the control line L11, will cause actuation of the tubing head safety valve to closed position. I

If desired, other sensing devices may be connected between the flanges of other components of the Christmas tree and a control fluid line L12 may be connected to the control fluid line L10 and L11 leading to the down-hole valve, for actuation of both the down-hole safety valve and the well head safety valve.

A still further modification of the flow controlling safety valve is shown in FIG. 15, wherein the valve closure member and seat are the same as those of the forms previously described. However, in this form of the device the valve is shown as mounted on a tubular member 400 which may be the lower end of a locking device or the tubing hanger of the well tubing head. The ball valve is shown as being movable mechanically to an open position by a prong or the like (not shown) and latched in such open position by means ofa ball detent mechanism 401 disposed within the housing 480 and acting on the elongate tubular valve seat and piston member 485 to hold such tubular member in the lower position in which the ball closure member 410 is turned to the open position, as shown. When the detent mechanism 401 is released, the spring 482 will bias the sleeve 485 upwardly to move the closure member 410 to closed position, the spring being confined between the upper end of the housing sub 507 and a split ring 508 mounted in an external annular groove 509 on the exterior mid-portion of the sleeve.

The detent mechanism 401 comprises a plurality of detent latching balls 425 which are disposed in lateral apertures 426 in the upper portion of an upwardly extending retainer sleeve 427a extending upwardly from an internal annular flange 427 in the mid-portion of the bore of the housing 480 and through which the enlarged external surface 485a of the sleeve 485 is slidable. An upwardly facing shoulder 428 formed on the external surface of the tubular seat sleeve 485 of the ball valve is engaged by the balls to hold the sleeve in the lower position shown in FIG. 15 when the balls are engaged with the seat. The halls are positively held inwardly in locking engagement with the seat by a locking detent or latching sleeve 429, the lower end of which has an internal annular releasing recess 430 formed therein into which the balls may move to permit the shoulder 428 to pass the balls when the sleeve is moved upwardly to position the recess in alignment or registry with the balls.

The upper portion of the locking sleeve 429 is reduced in both internal and external diameter to provide a core supporting stem or neck 435 slidable along the reduced upper end of tubular sleeve 485 and having an iron or other similar magnetic solenoid core sleeve 436 mounted in an external annular groove 437 formed along the exterior of the neck. The iron core sleeve may be split and suitably secured by welding or otherwise to the exterior of the neck. The locking sleeve 429 is biased downwardly toward the locking position shown in FIG. 15 by a helical coil spring 431 which is confined between the upwardly facing shoulder 432 at the lower end of the reduced neck 435 and the lower end of an electro-magnetic solenoid coil 440 confined within an enlarged bore 441 in the upper portion of the housing 480 of the valve. Electrical conductor wires 442 and 443 lead from the electrical coil 440 upwardly through a conduit 444 to a point exteriorly of the flow path of the well head and to a source of power 445 which may be a monostable multivibrator for supplying sufficient power to activate the solenoid detent latch sleeve. A sensing switch mechanism 450, which is a sensing mechanism similar to the sensing mechanism 35 of FIGS. 10 and 10-A, but is a normally closed switch held open by a plunger 451 disposed in a housing similar to the housing 36 of such sensing mechanism, is yieldable to permit the switch to move to its normally closed position to energize the coil 440 and cause the core 436 to move upwardly therewithin and lift the detent locking sleeve 427 to position the recess 430 in registry with the balls, whereupon the spring 482 will move the sleeve 485 upwardly to close the ball valve closure member 410. Thus, the valve is triggered by the electromagnetic solenoid type operating mechanism for moving the locking sleeve with respect to the detent balls 425 to release the sleeve for movement to closed position.

Still another form of the valve is shown in FIG. 16, wherein the elongate tubular valve seat sleeve 585 has a soft iron or other magnetic material solenoid core sleeve 536 secured on the exterior thereof in an external annular recess 537 formed on the upper portion of the sleeve. The electro-magnetic solenoid coil 540 is mounted in an internal annular recess 541 in the valve housing 580, similarly to the coil 440 of the form last described, and acts on the soft iron solenoid core 536 to draw the same downwardly to the position shown in FIG. 16 and move the valve seat sleeve 585 and the valve closure member 510 connected therewith to the open position. The coil 540 is connected by electrical conductors 542 and 543 to a source of electric power and a normally open switch 550, identical to that of FIG. 10, which is held open by a plunger 551 similar to that of the sensing device 35 of FIG. 10. The power unit 545 continues to supply energy to the solenoid coil 540 to hold the solenoid core 536 downwardly and retain the valve seat sleeve in the lower position and the valve closure open. When the button 551 is destroyed or the flanges between which it is positioned separate, the switch 550 is moved to its normally open position to cut off or disconnect the supply of power to the coil 540 and permit the sleeve 585 to be moved upwardly to the upper position by the helical coiled spring 582. In the upward position the ball closure member 510 is closed.

In this form of the device, the tubular member 500 at the upper end of the housing also may be either the lower end of an anchoring and sealing device I or the lower end ofa tubing hanger in the tubing head.

The electrically controlled flow control safety valves of FIGS. 15 and 16 show modifications of the valve adapted for using the sensing mechanisms of FIG. 10 and 10-A, though others may be used equally well.

It will be seen that improved methods, apparatus and systems for controlling flow of well fluids from a well flow conductor have been shown and described, and particularly that such methods, apparatus and systems are adapted to detect and control such flow when undesired and unsafe conditions occur in the flow path and connections of the well head Christmas tree.

The foregoing description of the invention is explanatory only, and changes in the details of the constructions illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

l. A method of controlling flow from a well having a bore penetrating a producing formation and a flow conduit disposed therein for conducting well fluids from such formation to a well head Christmas tree having a plurality of elements connected in sealing communication with each other therein and connected in flow communication with the upper end of said flow conduit, comprising the steps of: disposing flow controlling means in the flow conduit operable to control fluid flow therethrough; holding said flow controlling means open to permit flow of well fluids through the flow conduit; sensing at positions separated from said flow conduit a condition of the sealing connections of the elements of the well head Christmas tree which would permit undesired leaking of well fluids from within the flow conduit and said Christmas tree through said connections to the atmosphere exteriorly of said flow conduit and Christmas tree; and closing said flow controlling means in response to the sensing of such condition.

2. A method of controlling flow from a well having a bore penetrating a producing formation and a well flow conduit disposed therein having one end thereof in flow communication with said formation and the other end thereof connected to a Christmas tree having a plurality of elements connected in sealing communication with each other and a flow line connected with said Christmas tree establishing a flow path for conducting well fluids from the formation to the surface, comprising: disposing normally closed flow controlling valve means said flow path below said Christmas tree; holding said flow controlling valve means open by remote control fluid pressure to permit flow of well fluids through said flow path; establishing a closed control fluid pressure chamber in said Christmas tree separate from said flow path and communicating with one or more of the connections between adjacent components of the Christmas tree; maintaining said remote control fluid pressure in said closed pressure chamber in said Christmas tree for detecting a condition of said one or more connections between adjacent components of said Christmas tree which would release said control fluid pressure from said closed pressure chamber separate from said flow path to indicate a condition which would result in the undesired escape of well fluids from said flow path; and controlling closing of said flow controlling valve means by releasing the pressure of said control fluid in said closed pressure chamber between said adjacent components of said Christmas tree and acting on said valve means.

3. A well flow controlling system for use in a well having a flow conductor extending from the surface to the producing formation for conducting well fluids from the producing formation to the surface, a well head Christmas tree having a plurality of components connected in sealing communication with each other connected to the upper end of and communicating with the flow conductor and providing a flow path for receiving and conducting the well fluids from the flow conductor to the surface flow lines, flow controlling valve means disposed in the flow conductor operable between open and closed positions to control flow through the flow conductor, and remote control means at the surface for controlling actuation of said flow controlling valve means and including: sensing means separate from the flow path through the Christmas tree connected with the connection between two or more adjacent components of said well head Christmas tree for detecting a condition of said connection between said adjacent components of said Christmas tree which would result in permitting undesired leakage of fluids from the flow path therethrough; and means operatively connecting said sensing means with said remote control means for controlling operations of said valve to cause the valve to be moved from open to closed position upon the occurrence of such condition.

4. Apparatus for controlling flow from a well having a bore penetrating a producing formation and in which a tubing string is hung from a hanger at the surface and communicates at its lower end with the producing formation, and to which a Christmas tree having a plurality of components connected in sealing flow communication with each other is connected for flow communication with the tubing string to provide a flow path from the tubing to the surface flow lines, said apparatus including: a normally closed safety valve; means for supporting said safety valve at said tubing hanger for controlling flow of fluids from the tubing string through the flow path through the components of the Christmas tree; means for releasably holding said safety valve in open position; remote control means for controlling deactivation of said means for releasably holding said safety valve in open position and operable for deactivating said holding means to permit movement of said safety valve from open to closed position; and sensing means separate from the flow path through the components of said Christmas tree operatively connected with at least one connection between adjacent components of said Christmas tree for detecting a condition of the connection between said adjacent components thereof which would result in permitting undesired leakage of well fluids from the flow path therethrough; and means operatively connecting said sensing means with said control means for actuating said control means to deactivate said means for releasably holding said valve in open position to permit said valve to move to a normally closed position to cut off flow of well fluids from the tubing string to the flow path through the components of the Christmas tree.

5. Apparatus of the character set forth in claim 4 wherein said means for releasably holding said safety valve in open position comprises: a control fluid pressure applied to said safety valve from a remote point; and said control means comprises: a closed pressure chamber in said Christmas tree separate from the flow path therein and communicating with the connections between one or more of the components of the Christmas tree; said closed separate pressure chamber having control fluid pressure confined therein and communicating with said control fluid applied to said safety valve; and said sensing means for sensing a condition of said connections which would result in permitting undesired leakage of well fluid from said flow path includes means operative upon sensing such condition of said connections to release said control fluid pressure from said closed separate chamber to reduce the control fluid pressure applied to the safety valve and permit the safety valve to move from open to closed positron.

6. An apparatus of the character set forth in claim 4 wherein the means for supporting the safety valve at the tubing hanger comprises: a tubular valve receptacle formed in the tubing hanger and having locking and sealing surfaces therein engageable by said safety valve for closing off flow through the tubing string when said safety valve is closed, said safety valve being removable from said receptacle without disturbing the tubing hanger or tubing string.

7. Apparatus of the character set forth in claim 4 wherein said means for holding said valve in open position comprises an electromagnetic operated means in the valve; said remote control means comprises a source of electric power connected with said electromagnetic means in said valve; and said sensing means comprises a switch for controlling supply of power to said electromagnetic means and disposed in operative connection with at least one connection between adjacent components of said Christmas tree to sense and be operated as a result of movement of such connection between the components of the Christmas tree which would permit a leak of fluids from the flow path therethrough.

8. Apparatus of the character set forth in claim 4 wherein said sensing means comprises: heat sensitive means engaged with at least one connection between adjacent components of said Christmas tree and responsive to a temperature of said connection above a predetermined temperature for actuating the control means for deactivating the means releasably holding the valve in open position to release said means and permit the safety valve to close.

9. Apparatus of the character set forth in claim 4 wherein said normally closed safety valve comprises: down-hole flow control safety valve means connected in the tubing string substantially below the surface of the well and operable by remote control fluid means from the surface of the well.

10. Apparatus of the character set forth in claim 4 wherein: down-hole flow control safety valve means is connected in the tubing string substantially below the surface of the well and operable by remote control fluid means from the surface of the well, and actuation of said down-hole safety valve means is also controlled by said control means controlling actuation said safety valve supported at said tubing hanger, whereby both said down-hole safety valve and said safety valve supported at the tubing hanger are actuated by a common control means and responsive to a common sensing means.

11. A method of controlling flow from a well of the character set forth in claim 1, wherein the step of sensing the condition at the well head Christmas tree which would permit undesired leaking of well fluids from said Christmas tree to the atmosphere comprises: confining a a body of control fluid pressure in a closed chamber in said Christmas tree separated from the flow path through said Christmas tree; exposing said separate body of control fluid pressure to the connections between adjacent components of the well head; communicating said control fluid pressure of said separate chamber with a body of control fluid under pressure acting on said flow controlling means in the flow conduit and operable when the pressure of said confined body of control fluid pressure in said chamber in said well head Christmas tree is reduced by conditions at said con-nections between adjacent components of said Christmas tree opening said closed chamber to reduce the pressure of the control fluid acting on said flow controlling means to permit the flow controlling means to move to closed position to shut off flow through the well flow conductor.

12. A method of controlling flow from a well of the character set forth in claim 1, wherein the steps of sensing the condition at the connection between adjacent components of the well head Christmas tree which would permit undesired leaking of well fluids from said Christmas tree to the atmosphere comprises: sensing at the connection between adjacent components of the well head Christmas tree movement of said adjacent components with respect to each other opening the flow path through said Christmas tree to the atmosphere; and transmitting a signal from said connection movement sensing means to the flow controlling means in the well for causing the same to close.

13. A method of controlling flow from a well of the character set forth in claim 1, wherein the flow controlling means is installed in the well flow conduit at the well flow conduit hanger immediately below the Christmas tree.

14. A system of the character set forth in claim 3, wherein: the flow controlling valve disposed in the conductor is disposed in the hanger for the well flow conductor below the flow path through the Christmas tree.

15. A well flow controlling system of the character set forth in claim 3, wherein the sensing means connected with the well head Christmas tree comprises: a closed chamber in said Christmas tree separated from the flow path therethrough and communicating with the connection between adjacent components of the well head Christmas tree; and means confining control fluid under pressure in said chamber and communicating with the means for control-line operation of the valve means, whereby a leak occurring in said well head chamber will actuate said confining means to release control fluid from said chamber to reduce the pressure of the control fluid to cause the flow controlling valve means to move to closed position.

16. A flow control system of the character set forth in claim 3, wherein the sensing means comprises: means disposed between the coupling means connecting adjacent components of the well head Christmas tree for sensing movement of said components with respect to each other to cause activation of the means con-trolling operation of the valve to cause the valve to move to closed position.

17. A system of the character set forth in claim 3, wherein the flow controlling safety valve means is responsive to operating means for controlling movement of said valve means to closed position upon the occurrence of the undesired conditions at the Christmas tree.

18. A system of the character set forth in claim 3, wherein the sensing means includes: temperature responsive means engaged with the connection between adjacent components of the Christmas tree and operable by elevated temperatures for actuating the control means for controlling operation of the safety valve means to cause the safety valve means to move from closed to open position upon the occurrence of predetermined temperature at the well head Christmas tree.

19. A system of the character set forth in claim 16, wherein the sensing means also includes: a temperature responsive means in engagement with the connection between adjacent components of the Christmas tree and operable in response to temperature elevated above a predetermined temperature for actuating the control means for controlling operation of the safety valve means to cause the safety valve means to move from closed to open position upon the occurrence of said predetermined elevated temperature at the well head Christmas tree.

20. A method of controlling flow from a well having well casing penetrating to a producing formation and a flow conduit disposed therein for conducting well fluids from such formation to a well head Christmas tree having a plurality of separate components connected together in sealing communication providing a flow path therethrough connected in flow communication with the upper end of said flow conduit and having surface flow lines connected thereto, comprising: closing the upper end of the flow conduit below the well head Christmas tree; disconnecting the well head Christmas tree from the well casing and upper end of the flow while the flow conduit is closed; providing sensing means at one or more connections between adjacent components of the Christmas tree separated from the flow path therethrough for sensing conditions at said connection which would result in opening said flow path to permit undesired escape of well fluids from said flow path; inserting a tubular spacer means on the upper end of said well casing and the upper end of said well flow conduit to communicate with the flow path of the well head Christmas tree; connecting the well head Christmas tree to the spacer means; removing the closure from the flow conduit; installing a flow controlling safety valve in the flow conduit below the well head Christmas tree operable to control fluid flow through the flow conduit; holding said flow controlling safety valve open to permit flow of well fluids through the well conduit; operatively connecting said sensing means with said holding means for deactivating said holding means upon said sensing means sensing an undesirable condition at a connection between components of the well head Christmas tree; and closing said flow controlling safety valve in response to the sensing of such condition and deactivation of said holding means.

21. A method of the character set forth in claim 20 including the step of sensing a condition of movement between adjacent connected components of the Christmas tree resulting in opening the connection between the components of the well head Christmas tree at the surface which would permit undesired leaking of well fluids from said Christmas tree to the atmosphere and closing said flow controlling safety valve in response to such condition.

22. A method of controlling flow from a well having well casing penetrating to a producing formation and having a tubing head at its upper end with a hanger for supporting a flow conduit disposed in said casing therein for conducting well fluids from such formation to a well head Christmas tree connected to said tubing head and having a flow path therethrough connected in flow communication with the upper end of said flow conduit and having surface flow lines connected thereto, comprising: closing the upper end of the flow conduit at the hanger below the well head Christmas tree; disconnecting the well head Christmas tree from the tubing head and upper end of the flow conduit while the flow conduit is closed; inserting a tubular spacer member on the upper end of said tubing head for flow communication with the upper end of said well flow conduit and disposed to communicate with the flow path of the well head Christmas tree; connecting the well head Christmas tree to the spacer; removing the closure from the hanger for the flow conduit; installing a flow controlling safety valve in the hanger for the flow conduit below the well head Christmas tree operable to control fluid flow through the flow conduit; establishing a closed pressure chamber in said spacer member and hanger for the upper end of the flow conduit separate from the flow path through said Christmas tree and communicating with one or more of the connections between the tubing head and the spacer member and the well head Christmas tree thereabove; holding said flow controlling valve means open by remote control fluid pressure to permit flow of well fluids through said flow path; maintaining said control fluid pressure also in said pressure chamber for detecting a condition of said one or more connections which would result in undesired escape of well fluids from said flow path; and closing said flow controlling safety valve upon reduction of the pressure of said control fluids in said chamber and acting on said safety valve to close off flow of well fluids through said flow conduit.

23. A method of the character set forth in claim 22, including positioning the well flow controlling safety valve in sealing engagement with the bore of the spacer means above the well casing and below the Christmas tree and sealing with the upper end of the well conduit below said spacer means for defining said closed pressure chamber and directing control fluid pressure into said chamber and to said safety valve to control the operation of said safety valve.

24. A method of controlling flow from a well having well casing penetrating to a producing formation and a tubing head connected to the upper end of said casing with a hanger therein connected to the upper end of a flow conduit disposed in said casing for conducting well fluids from such formation to a well head Christmas tree having a plurality of separate components connected together in sealing communication to provide a flow path therethrough and connected in flow communication with the upper end of said flow conduit and having surface flow lines connected thereto, comprising: closing the upper end of the flow conduit at the hanger below the well head Christmas tree; disconnecting the well head Christmas tree from the tubing head and hanger supporting the flow conduit while the flow conduit is closed; inserting a tubular spacer means on the upper end of said tubing head and the hanger at the upper end of said well flow conduit to communicate with the well flow conduit and with the flow path of the well head Christmas tree; connecting the well head Christmas tree to the spacer means; providing sensing means at each of the connections between the tubing head, the spacer means and each of the components of the Christmas tree separated from the flow path therethrough for sensing conditions at each of said connections which would permit undesired escape of well fluids from said flow path; removing the closure from the flow conduit; installing a flow controlling safety valve in the hanger and the upper end of the flow conduit below the well head Christmas tree operable to control fluid flow through the flow conduit; holding said flow controlling safety valve open to permit flow of 

1. A method of controlling flow from a well having a bore penetrating a producing formation and a flow conduit disposed therein for conducting well fluids from such formation to a well head Christmas tree having a plurality of elements connected in sealing communication with each other therein and connected in flow communication with the upper end of said flow conduit, comprising the steps of: disposing flow controlling means in the flow conduit operable to control fluid flow therethrough; holding said flow controlling means open to permit flow of well fluids through the flow conduit; sensing at positions separated from said flow conduit a condition of the sealing connections of the elements of the well head Christmas tree which would permit undesired leaking of well fluids from within the flow conduit and said Christmas tree through said connections to the atmosphere exteriorly of said flow conduit and Christmas tree; and closing said flow controlling means in response to the sensing of such condition.
 2. A method of controlling flow from a well having a bore penetrating a producing formation and a well flow conduit disposed therein having one end thereof in flow communication with said formation and the other end thereof connected to a Christmas tree having a plurality of elements connected in sealing communication with each other and a flow line connected with said Christmas tree establishing a flow path for conducting well fluids from the formation to the surface, comprising: disposing normally closed flow controlling valve means said flow path below said Christmas tree; holding said flow controllIng valve means open by remote control fluid pressure to permit flow of well fluids through said flow path; establishing a closed control fluid pressure chamber in said Christmas tree separate from said flow path and communicating with one or more of the connections between adjacent components of the Christmas tree; maintaining said remote control fluid pressure in said closed pressure chamber in said Christmas tree for detecting a condition of said one or more connections between adjacent components of said Christmas tree which would release said control fluid pressure from said closed pressure chamber separate from said flow path to indicate a condition which would result in the undesired escape of well fluids from said flow path; and controlling closing of said flow controlling valve means by releasing the pressure of said control fluid in said closed pressure chamber between said adjacent components of said Christmas tree and acting on said valve means.
 3. A well flow controlling system for use in a well having a flow conductor extending from the surface to the producing formation for conducting well fluids from the producing formation to the surface, a well head Christmas tree having a plurality of components connected in sealing communication with each other connected to the upper end of and communicating with the flow conductor and providing a flow path for receiving and conducting the well fluids from the flow conductor to the surface flow lines, flow controlling valve means disposed in the flow conductor operable between open and closed positions to control flow through the flow conductor, and remote control means at the surface for controlling actuation of said flow controlling valve means and including: sensing means separate from the flow path through the Christmas tree connected with the connection between two or more adjacent components of said well head Christmas tree for detecting a condition of said connection between said adjacent components of said Christmas tree which would result in permitting undesired leakage of fluids from the flow path therethrough; and means operatively connecting said sensing means with said remote control means for controlling operations of said valve to cause the valve to be moved from open to closed position upon the occurrence of such condition.
 4. Apparatus for controlling flow from a well having a bore penetrating a producing formation and in which a tubing string is hung from a hanger at the surface and communicates at its lower end with the producing formation, and to which a Christmas tree having a plurality of components connected in sealing flow communication with each other is connected for flow communication with the tubing string to provide a flow path from the tubing to the surface flow lines, said apparatus including: a normally closed safety valve; means for supporting said safety valve at said tubing hanger for controlling flow of fluids from the tubing string through the flow path through the components of the Christmas tree; means for releasably holding said safety valve in open position; remote control means for controlling deactivation of said means for releasably holding said safety valve in open position and operable for deactivating said holding means to permit movement of said safety valve from open to closed position; and sensing means separate from the flow path through the components of said Christmas tree operatively connected with at least one connection between adjacent components of said Christmas tree for detecting a condition of the connection between said adjacent components thereof which would result in permitting undesired leakage of well fluids from the flow path therethrough; and means operatively connecting said sensing means with said control means for actuating said control means to deactivate said means for releasably holding said valve in open position to permit said valve to move to a normally closed position to cut off flow of well fluids from the tubing string to the flow path through the components of the Christmas tree.
 5. Apparatus of the character set forth in claim 4 wherein said means for releasably holding said safety valve in open position comprises: a control fluid pressure applied to said safety valve from a remote point; and said control means comprises: a closed pressure chamber in said Christmas tree separate from the flow path therein and communicating with the connections between one or more of the components of the Christmas tree; said closed separate pressure chamber having control fluid pressure confined therein and communicating with said control fluid applied to said safety valve; and said sensing means for sensing a condition of said connections which would result in permitting undesired leakage of well fluid from said flow path includes means operative upon sensing such condition of said connections to release said control fluid pressure from said closed separate chamber to reduce the control fluid pressure applied to the safety valve and permit the safety valve to move from open to closed position.
 6. An apparatus of the character set forth in claim 4 wherein the means for supporting the safety valve at the tubing hanger comprises: a tubular valve receptacle formed in the tubing hanger and having locking and sealing surfaces therein engageable by said safety valve for closing off flow through the tubing string when said safety valve is closed, said safety valve being removable from said receptacle without disturbing the tubing hanger or tubing string.
 7. Apparatus of the character set forth in claim 4 wherein said means for holding said valve in open position comprises an electromagnetic operated means in the valve; said remote control means comprises a source of electric power connected with said electromagnetic means in said valve; and said sensing means comprises a switch for controlling supply of power to said electromagnetic means and disposed in operative connection with at least one connection between adjacent components of said Christmas tree to sense and be operated as a result of movement of such connection between the components of the Christmas tree which would permit a leak of fluids from the flow path therethrough.
 8. Apparatus of the character set forth in claim 4 wherein said sensing means comprises: heat sensitive means engaged with at least one connection between adjacent components of said Christmas tree and responsive to a temperature of said connection above a predetermined temperature for actuating the control means for deactivating the means releasably holding the valve in open position to release said means and permit the safety valve to close.
 9. Apparatus of the character set forth in claim 4 wherein said normally closed safety valve comprises: down-hole flow control safety valve means connected in the tubing string substantially below the surface of the well and operable by remote control fluid means from the surface of the well.
 10. Apparatus of the character set forth in claim 4 wherein: down-hole flow control safety valve means is connected in the tubing string substantially below the surface of the well and operable by remote control fluid means from the surface of the well, and actuation of said down-hole safety valve means is also controlled by said control means controlling actuation said safety valve supported at said tubing hanger, whereby both said down-hole safety valve and said safety valve supported at the tubing hanger are actuated by a common control means and responsive to a common sensing means.
 11. A method of controlling flow from a well of the character set forth in claim 1, wherein the step of sensing the condition at the well head Christmas tree which would permit undesired leaking of well fluids from said Christmas tree to the atmosphere comprises: confining a a body of control fluid pressure in a closed chamber in said Christmas tree separated from the flow path through said Christmas tree; exposing said separAte body of control fluid pressure to the connections between adjacent components of the well head; communicating said control fluid pressure of said separate chamber with a body of control fluid under pressure acting on said flow controlling means in the flow conduit and operable when the pressure of said confined body of control fluid pressure in said chamber in said well head Christmas tree is reduced by conditions at said con-nections between adjacent components of said Christmas tree opening said closed chamber to reduce the pressure of the control fluid acting on said flow controlling means to permit the flow controlling means to move to closed position to shut off flow through the well flow conductor.
 12. A method of controlling flow from a well of the character set forth in claim 1, wherein the steps of sensing the condition at the connection between adjacent components of the well head Christmas tree which would permit undesired leaking of well fluids from said Christmas tree to the atmosphere comprises: sensing at the connection between adjacent components of the well head Christmas tree movement of said adjacent components with respect to each other opening the flow path through said Christmas tree to the atmosphere; and transmitting a signal from said connection movement sensing means to the flow controlling means in the well for causing the same to close.
 13. A method of controlling flow from a well of the character set forth in claim 1, wherein the flow controlling means is installed in the well flow conduit at the well flow conduit hanger immediately below the Christmas tree.
 14. A system of the character set forth in claim 3, wherein: the flow controlling valve disposed in the conductor is disposed in the hanger for the well flow conductor below the flow path through the Christmas tree.
 15. A well flow controlling system of the character set forth in claim 3, wherein the sensing means connected with the well head Christmas tree comprises: a closed chamber in said Christmas tree separated from the flow path therethrough and communicating with the connection between adjacent components of the well head Christmas tree; and means confining control fluid under pressure in said chamber and communicating with the means for control-line operation of the valve means, whereby a leak occurring in said well head chamber will actuate said confining means to release control fluid from said chamber to reduce the pressure of the control fluid to cause the flow controlling valve means to move to closed position.
 16. A flow control system of the character set forth in claim 3, wherein the sensing means comprises: means disposed between the coupling means connecting adjacent components of the well head Christmas tree for sensing movement of said components with respect to each other to cause activation of the means con-trolling operation of the valve to cause the valve to move to closed position.
 17. A system of the character set forth in claim 3, wherein the flow controlling safety valve means is responsive to operating means for controlling movement of said valve means to closed position upon the occurrence of the undesired conditions at the Christmas tree.
 18. A system of the character set forth in claim 3, wherein the sensing means includes: temperature responsive means engaged with the connection between adjacent components of the Christmas tree and operable by elevated temperatures for actuating the control means for controlling operation of the safety valve means to cause the safety valve means to move from closed to open position upon the occurrence of predetermined temperature at the well head Christmas tree.
 19. A system of the character set forth in claim 16, wherein the sensing means also includes: a temperature responsive means in engagement with the connection between adjacent components of the Christmas tree and operable in response to temperature elevated above a predetermined temperature for actuating the control means for controlling operation of the safety valve means to cause the safety valve means to move from closed to open position upon the occurrence of said predetermined elevated temperature at the well head Christmas tree.
 20. A method of controlling flow from a well having well casing penetrating to a producing formation and a flow conduit disposed therein for conducting well fluids from such formation to a well head Christmas tree having a plurality of separate components connected together in sealing communication providing a flow path therethrough connected in flow communication with the upper end of said flow conduit and having surface flow lines connected thereto, comprising: closing the upper end of the flow conduit below the well head Christmas tree; disconnecting the well head Christmas tree from the well casing and upper end of the flow while the flow conduit is closed; providing sensing means at one or more connections between adjacent components of the Christmas tree separated from the flow path therethrough for sensing conditions at said connection which would result in opening said flow path to permit undesired escape of well fluids from said flow path; inserting a tubular spacer means on the upper end of said well casing and the upper end of said well flow conduit to communicate with the flow path of the well head Christmas tree; connecting the well head Christmas tree to the spacer means; removing the closure from the flow conduit; installing a flow controlling safety valve in the flow conduit below the well head Christmas tree operable to control fluid flow through the flow conduit; holding said flow controlling safety valve open to permit flow of well fluids through the well conduit; operatively connecting said sensing means with said holding means for deactivating said holding means upon said sensing means sensing an undesirable condition at a connection between components of the well head Christmas tree; and closing said flow controlling safety valve in response to the sensing of such condition and deactivation of said holding means.
 21. A method of the character set forth in claim 20 including the step of sensing a condition of movement between adjacent connected components of the Christmas tree resulting in opening the connection between the components of the well head Christmas tree at the surface which would permit undesired leaking of well fluids from said Christmas tree to the atmosphere and closing said flow controlling safety valve in response to such condition.
 22. A method of controlling flow from a well having well casing penetrating to a producing formation and having a tubing head at its upper end with a hanger for supporting a flow conduit disposed in said casing therein for conducting well fluids from such formation to a well head Christmas tree connected to said tubing head and having a flow path therethrough connected in flow communication with the upper end of said flow conduit and having surface flow lines connected thereto, comprising: closing the upper end of the flow conduit at the hanger below the well head Christmas tree; disconnecting the well head Christmas tree from the tubing head and upper end of the flow conduit while the flow conduit is closed; inserting a tubular spacer member on the upper end of said tubing head for flow communication with the upper end of said well flow conduit and disposed to communicate with the flow path of the well head Christmas tree; connecting the well head Christmas tree to the spacer; removing the closure from the hanger for the flow conduit; installing a flow controlling safety valve in the hanger for the flow conduit below the well head Christmas tree operable to control fluid flow through the flow conduit; establishing a closed pressure chamber in said spacer member and hanger for the upper end of the flow conduit separate from the flow path through said Christmas tree and communicating with one or more of the connections beTween the tubing head and the spacer member and the well head Christmas tree thereabove; holding said flow controlling valve means open by remote control fluid pressure to permit flow of well fluids through said flow path; maintaining said control fluid pressure also in said pressure chamber for detecting a condition of said one or more connections which would result in undesired escape of well fluids from said flow path; and closing said flow controlling safety valve upon reduction of the pressure of said control fluids in said chamber and acting on said safety valve to close off flow of well fluids through said flow conduit.
 23. A method of the character set forth in claim 22, including positioning the well flow controlling safety valve in sealing engagement with the bore of the spacer means above the well casing and below the Christmas tree and sealing with the upper end of the well conduit below said spacer means for defining said closed pressure chamber and directing control fluid pressure into said chamber and to said safety valve to control the operation of said safety valve.
 24. A method of controlling flow from a well having well casing penetrating to a producing formation and a tubing head connected to the upper end of said casing with a hanger therein connected to the upper end of a flow conduit disposed in said casing for conducting well fluids from such formation to a well head Christmas tree having a plurality of separate components connected together in sealing communication to provide a flow path therethrough and connected in flow communication with the upper end of said flow conduit and having surface flow lines connected thereto, comprising: closing the upper end of the flow conduit at the hanger below the well head Christmas tree; disconnecting the well head Christmas tree from the tubing head and hanger supporting the flow conduit while the flow conduit is closed; inserting a tubular spacer means on the upper end of said tubing head and the hanger at the upper end of said well flow conduit to communicate with the well flow conduit and with the flow path of the well head Christmas tree; connecting the well head Christmas tree to the spacer means; providing sensing means at each of the connections between the tubing head, the spacer means and each of the components of the Christmas tree separated from the flow path therethrough for sensing conditions at each of said connections which would permit undesired escape of well fluids from said flow path; removing the closure from the flow conduit; installing a flow controlling safety valve in the hanger and the upper end of the flow conduit below the well head Christmas tree operable to control fluid flow through the flow conduit; holding said flow controlling safety valve open to permit flow of well fluids through the well conduit; operatively connecting each of said sensing means with said holding means for deactivating said holding means upon any one of said sensing means sensing an undesirable or unsafe condition at any one of the connections between the tubing head, at spacer means, or any of the components of the well head Christmas tree; and closing said flow controlling safety valve in response to the sensing of such condition and deactivation of said holding means. 